Smart & Aggressive
attorneys defending you.
click for a free consultation

How reliable are field sobriety tests?

Posted on October 9, 2019 in DUI defense

Standard Field Sobriety Tests (SFST) have been used by police in Arizona to detect alcohol-impaired drivers for nearly 30 years. The tests were developed by the National Highway Traffic Safety Administration (NHTSA), which first began researching standardized tests in the 1970s.

But how accurate are they? There’s much debate over the topic with some claiming the tests have proven to be 90% accurate for detecting DUI when administered by a trained officer. However, according to the DUI DWI Foundation, the tests are reliable in only 65% to 77% of all cases.

What are the three tests?

The Standard Field Sobriety Test is a three-step exam designed to gauge whether drivers blood alcohol concentration (BAC) exceeds the legal limit of 0.08%. The three tests are:

  • Horizontal gaze nystagmus: An officer will shine a light in your eyes looking for involuntary jerking of the eyeballs
  • Walk-and-turn: You will be directed to take several steps heel-to-toe in a straight line to check your balance and ability to follow instructions
  • One-leg stand: The officer will ask you to raise one foot six inches off the ground and hold for 30 seconds to see whether you can maintain your balance

Reasons for failing a test

NHTSA says there is a 65% chance the driver’s BAC is 0.10% or higher if they fail two or more of the tests. Failing one can result in an officer requesting that the driver take a breath or chemical test to confirm their suspicions. Trained officers will usually ask drivers whether there is any reason they could fail the test. These reasons can include:

  • Certain medical conditions
  • Disabilities
  • Age
  • Injury
  • Medications
  • Wearing contact lenses

Seek legal advice if charged with DUI

Arizona has some of the strictest DUI laws in the nation, and a conviction can have long-lasting consequences, such as jail time, extensive fines and fees, driving restrictions and insurers doubling or tripling insurance rates.

An experienced DUI attorney will protect your rights by making sure an officer had probable cause to stop you and correctly performed SFSTs and other tests. Just because you fail a test doesn’t mean you are guilty. A successful defense can reduce jail time and fines and, in some cases, lead to charges being dropped.

Contact Us


  • All fields required *
  • This field is for validation purposes and should be left unchanged.
  • This field is for validation purposes and should be left unchanged.